1. Field of the Invention
The present invention relates to a liquid crystal display device and a fabricating method thereof, and more particularly to a liquid crystal display device that may reduce manufacturing cost, contribute to a thin profile, and generate a uniform brightness, and a fabricating method thereof.
2. Discussion of the Related Art
Liquid crystal display devices are widely used due to their being light weight, having a thin profile and low power consumption, for example. As a result, the liquid crystal display device is used in office automation equipment and audio/video equipment, for example. The liquid crystal display device controls the amount of light in accordance with a signal applied to a plurality of control switches that are arranged in a matrix, thereby displaying a desired picture on a screen.
As such, the liquid crystal display device is not a self luminous display device, thus it requires a separate light source such as a backlight.
Backlights may be largely classified as either direct type or edge type in accordance with the location of a light source. The edge type backlight has a light source installed at the edge of one side of a liquid crystal display device, and the edge type backlight irradiates light from the light source to a liquid crystal display panel through a light guide plate and a plurality of optical sheets. The direct type backlight has a plurality of light sources disposed directly under the liquid crystal display device, and the direct type backlight irradiates light from the light sources to the liquid crystal display panel through a diffusion plate and a plurality of optical sheets.
Recently, the direct type backlight which has improved brightness, light uniformity and color purity, versus the edge type backlight, is more often used in LCD TVs.
FIG. 1 is a diagram showing a liquid crystal display device of the related art to which the direct type backlight is applied.
Referring to FIG. 1, the liquid crystal display device of the related art includes a liquid crystal display panel 11 and a backlight unit 10. Herein, the liquid crystal display panel 11 displays an image, and the backlight unit 10 irradiates light to the liquid crystal display panel 11.
A plurality of data lines and a plurality of gate lines (not shown in FIG. 1) are arranged to cross each other at the liquid crystal display panel 11. Liquid crystal cells are arranged in a matrix type between an upper substrate and a lower substrate. Furthermore, pixel electrodes and common electrodes (not shown), which apply an electric field to each liquid crystal cell, are formed at the liquid crystal display panel 11. Thin film transistors (not shown) are formed at a crossing part of the plurality of data lines and the plurality of gate lines. Herein, the thin film transistors TFT switch a data voltage to be applied to a pixel electrode in response to a scanning signal. Gate drive integrated circuits and data drive integrated circuits are electrically connected, via a tape carrier package TCP (not shown), to the liquid crystal display panel 11.
The backlight unit 10 includes a plurality of lamps 15, a bottom cover 12, a diffusion plate 13, and a plurality of optical sheets 14.
The lamps 15 are radiated by an AC high voltage from an inverter (not shown) to supply a light to the diffusion plate 13.
The bottom cover 12 is manufactured in a container structure where the plurality of lamps 15 are received at an inner space, and a reflection plate is formed at a bottom and a side surface of the inner space. The diffusion plate 13 is assembled together with the bottom cover 12. The diffusion plate 13 may include a plurality of beads, and disperses light, using the beads, which is incident from a lamp. Accordingly, the diffusion plate 13 can minimize a brightness difference which is generated by a distance difference between the liquid crystal display panel and the lamp and a distance difference between the lamps. Since the diffusion plate 13 is such that the beads are spread into a medium having the same refractive index, the diffusion plate 13 cannot condense light.
The optical sheets 14 include at least one diffusion sheet and at least one prism sheet to uniformly irradiate light incident from the diffusion plate 13 to an entire liquid crystal display panel 11. Furthermore, the optical sheets 14 diffract a light progressing path toward a vertical direction regarding a display surface of liquid crystal display panel 11 to condense a light to a front surface of display surface of the liquid crystal display panel 11.
The lamp 15 may largely be classified into a cold cathode fluorescent lamp (hereinafter, referred to as “CCFL”), an external electrode fluorescent lamp (hereinafter, referred to as “EEFL”), and a light emitting diode (hereinafter, referred to as “LED”).
The liquid crystal display device of the related art keeps a distance between the liquid crystal display panel 11 and the lamps 15 in order to reduce a brightness difference between the lamps 15 to widen a diffusion space of light which is generated from the lamps 15, and installs a plurality of lamps 15 to narrow a distance between the lamps 15. Accordingly, the liquid crystal display device of the related art has a disadvantage in that a thickness increases and manufacturing cost is increased. Furthermore, in the liquid crystal display device of the related art, since there is a limit to maintaining a distance between the liquid crystal display panel 11 and the lamps 15 and increase in the number of the lamps 15, there is a limit to generating a uniform brightness.